This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This noninvasive pilot study from a postdoctoral fellow in HVI, under the direction of senior HVI investigators, intends to study mechanisms that regulate the coronary circulation in normal and pathophysiological conditions. Specifically, they wish to examine oxidative stress effects on coronary endothelial function and related cardiac functional alterations in overweight children and adolescents. 90 subjects will be recruited over a two year period for two studies. The first study will recruit 20 normal controls and 50 overweight children (ages 6-20) from the Dept of Pediatrics and will examine coronary vasoconstrictor and myocardial function following hyperoxia. Noninvasive transthoracic echocardiography will measure coronary flow resistance and systolic and diastolic function following 100% oxygen for 10 minutes. Measurements include: Body weight, waist and hip circumference;EKG heart rate monitoring;Blood pressure monitoring;2-D and Doppler echocardiogram;Facemask and ear clip oximeter to measure oxygen saturation. The second study is for overweight boys from the HMC weight management program, aged 14-20, participating in a 4-week weight loss camp (Camp Lion). The procedures from study one will be performed before and after the 4 week weight loss program. Total study visit time is approximately one hour/subject.